Fuel Cell with Fuel Monitoring System and Method of Use

ABSTRACT

A fuel cell ( 9 ) includes a removable and replaceable fuel supply ( 12 ) having fuel disposed therein. A system for monitoring various parameters of the fuel such as temperature, pressure, and the levels of dissolved oxygen is provided. A plurality of sensors ( 30 ) is disposed on the fuel supply side that is capable of communicating with a controller ( 18 ) and memory ( 13 ) on the fuel cell side. In another embodiment, at least one sensor for measuring a system parameter of the fuel communicates with an RFID tag ( 50 ) either remotely or via a hardwired link. The sensor and/or the RFID tag may be coated with a substance impervious to the caustic fuel. An RFID reader station collects the data. The controller may be included to use the data in real time to alter system parameters, such as fuel pumping rates or a bleed off, or to trigger a signal, such as to notify a user of an empty fuel supply. In another embodiment, an optical sensor ( 61, 102 ) may be used.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of commonly owned, co-pendingU.S. application Ser. No. 11/196,685, filed on Aug. 2, 2005, thedisclosures of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to fuel cells and monitoringtechnologies. In particular, sensor arrays linked to a remote controlsystem and information storage device are used to monitor systemparameters in a fuel cell.

BACKGROUND OF THE INVENTION

Fuel cells are devices that directly convert chemical energy ofreactants, i.e., fuel and oxidant, into direct current (DC) electricity.For an increasing number of applications, fuel cells are more efficientthan conventional power generation, such as combustion of fossil fuel,as well as portable power storage, such as lithium-ion batteries.

In general, fuel cell technology includes a variety of different fuelcells, such as alkali fuel cells, polymer electrolyte fuel cells,phosphoric acid fuel cells, molten carbonate fuel cells, solid oxidefuel cells and enzyme fuel cells. Today's more important fuel cells canbe divided into several general categories, namely: (i) fuel cellsutilizing compressed hydrogen (H₂) as fuel; (ii) proton exchangemembrane (PEM) fuel cells that use alcohols, e.g., methanol (CH₃OH),metal hydrides, e.g., sodium borohydride (NaBH₄), hydrocarbons, or otherfuels reformed into hydrogen fuel; (iii) PEM fuel cells that can consumenon-hydrogen fuel directly or direct oxidation fuel cells; and (iv)solid oxide fuel cells (SOFC) that directly convert hydrocarbon fuels toelectricity at high temperature.

Compressed hydrogen is generally kept under high pressure and istherefore difficult to handle. Furthermore, large storage tanks aretypically required and cannot be made sufficiently small for consumerelectronic devices. Conventional reformat fuel cells require reformersand other vaporization and auxiliary systems to convert fuels tohydrogen to react with oxidant in the fuel cell. Recent advances makereformer or reformat fuel cells promising for consumer electronicdevices. The most common direct oxidation fuel cells are direct methanolfuel cells or DMFC. Other direct oxidation fuel cells include directethanol fuel cells and direct tetramethyl orthocarbonate fuel cells.DMFC, in which methanol is reacted directly with oxidant in the fuelcell, has promising power application for consumer electronic devices.SOFC convert hydrocarbon fuels, such as butane, at high heat to produceelectricity. SOFC requires relatively high temperature in the range of1000° C. for the fuel cell reaction to occur.

The chemical reactions that produce electricity are different for eachtype of fuel cell. For DMFC, the chemical-electrical reaction at eachelectrode and the overall reaction for a direct methanol fuel cell aredescribed as follows:

Half-reaction at the anode:

CH₃OH+H₂O→CO₂+6H⁺+6e ⁻

Half-reaction at the cathode:

1.5O₂+6H⁺+6e ⁻→3H₂O

The overall fuel cell reaction:

CH₃OH+1.5O₂→CO₂+2H₂O

Due to both the migration of the hydrogen ions (H⁺) through the PEM fromthe anode to the cathode and the inability of the free electrons (e⁻) topass through the PEM, the electrons flow through an external circuit,thereby producing an electrical current. The external circuit may beused to power many useful consumer electronic devices, such as mobile orcell phones, calculators, personal digital assistants, laptop computers,and power tools, among others.

DMFC is discussed in U.S. Pat. Nos. 5,992,008 and 5,945,231, which areincorporated herein by reference in their entireties. Generally, the PEMis made from a polymer, such as Nafion® available from DuPont, which isa perfluorinated sulfonic acid polymer having a thickness in the rangeof about 0.05 mm to about 0.5 mm, or other suitable membranes. The anodeis typically made from a Teflonized carbon paper support with a thinlayer of catalyst, such as platinum-ruthenium, deposited thereon. Thecathode is typically a gas diffusion electrode in which platinumparticles are bonded to one side of the membrane.

In another direct oxidation fuel cell, borohydride fuel cell (DBFC)reacts as follows:

Half-reaction at the anode:

BH₄-+8OH—→BO₂ ⁻ +6H₂O+8e-

Half-reaction at the cathode:

2O₂+4H₂O+8e-→8OH—

In a chemical metal hydride fuel cell, generally aqueous sodiumborohydride is reformed and reacts as follows:

NaBH₄+2H₂O→(heat or catalyst)→4(H₂)+(NaBO₂)

Half-reaction at the anode:

H₂→2H++2 e ⁻

Half-reaction at the cathode:

2(2H⁺+2e ⁻)+O₂→2H₂O

Suitable catalysts for this reaction include platinum and ruthenium, aswell as other metals. The hydrogen fuel produced from reforming sodiumborohydride is reacted in the fuel cell with an oxidant, such as O₂, tocreate electricity (or a flow of electrons) and water byproduct. Asodium borate (NaBO₂) byproduct is also produced by this process. Asodium borohydride fuel cell is discussed in U.S. Pat. No. 4,261,956,which is incorporated herein by reference. Therefore, the known chemicalhydride reactions that use aqueous metal hydride have about 9 to 12weight percentage storage expectancy, and the liquid and the catalystused in the wet chemical reaction system need to be closely monitored.Additionally, it is difficult to maintain the stability of a metalhydride solution over a long period of time, because according to theformula t½−pH*log(0.034+kT), which provides the half life of thereaction, the reaction of hydrolysis always occurs very slowly.Furthermore, if the solution is stabilized, the reactivity is notcomplete.

In a hydride storage method, the reaction is as follows:

Metal+H₂→hydride+heat

However, storage expectancy of such a reaction is only about 5 weightpercentage. Additionally, such reactions can be expensive and difficultto package.

Another known method to produce hydrogen is a dry hydride reaction. Dryreaction, generally, involves the following reaction:

X(BH₄)→H₂, where X includes, but is not limited to, Na, Mg, Li, etc.

Again, dry reactions have several disadvantages, such as having astorage expectancy of only about 10 weight percentage, and the need toclosely monitor the pressure.

An additional method to produce hydrogen gas is by a pressure storagemethod using the formula PV=nRT, wherein P is pressure, V is volume, nis a number of moles, R is the gas constant, and T is temperature. Thismethod requires constant pressure monitoring.

One of the most important features for fuel cell application is fuelstorage. Another important feature is regulating the transport of fuelout of the fuel cartridge to the fuel cell. To be commercially useful,fuel cells such as DMFC or PEM systems should have the capability ofstoring sufficient fuel to satisfy the consumers' normal usage. Forexample, for mobile or cell phones, for notebook computers, and forpersonal digital assistants (PDAs), fuel cells need to power thesedevices for at least as long as the current batteries and, preferably,much longer. Additionally, the fuel cells should have easily replaceableor refillable fuel tanks to minimize or obviate the need for lengthyrecharges required by today's rechargeable batteries.

In the operation of a fuel cell, monitoring various system parameters inreal time is highly desirable for a number of reasons. First, trackingthe fuel usage history indicates the amount of fuel remaining in thefuel supply and provides the user with information regarding theremaining useful life of the fuel supply. The patent literaturediscloses a number of containers for consumable substances that includeelectronic memory components. United States patent applicationpublication no. US 2002/0154815, which is incorporated herein in itsentirety by reference, discloses a variety of containers that mayinclude read-only memories, programmable read-only memories,electronically erasable programmable read-only memories, non-volatilerandom access memories, volatile random access memories or other typesof electronic memory. These electronic memory devices may be used toretain coded recycle, refurbishing and/or refilling instructions for thecontainers, as well as a record of the use of the containers. Thecontainers may comprise liquid ink or powdered toner for a printer.Alternatively, the containers or fuel supply may comprise a fuel cell ora fuel supply therefor.

Also, the transfer of the fuel from the fuel supply to the fuel cell maydepend upon, inter alia, the viscosity of the fuel. For example, theviscosity of methanol, which is about 8.17×10⁻⁴ Pa-s at 1 atmosphere and0° C., drops to about 4.5×10⁻⁴ Pa-s at 1 atmosphere and 40° C.,representing about a 50% reduction. If the system is able to detect inreal time the temperature and/or pressure of the fuel contained withinthe fuel supply, then the fuel cell can self-regulate how long a fuelpump should run in order to provide an appropriate amount of fuel. Asfuel is supplied at the optimum rate, the efficiency of the system isincreased. Also, monitoring the pressure of the fuel within the fuelsupply can alert the user or the system of unacceptable high orunacceptable low pressure levels. Furthermore, the usable life of thefuel cell can be increased if exposure to fuel is limited to the amountof fuel necessary for operation. In other words, flooding the fuel cellwith excess fuel may damage the fuel cell.

One option among others for a monitoring system is using a radiofrequency identification (RFID) system. Systems using RFID technologiesare well known, particularly for uses such as tracking inventory such aslibrary or retail store inventory, automated payment systems such aspasses for toll booths, and security systems such as smart keys forstarting a car. Such systems may be large and active systems, utilizingbattery-powered transceiver circuitry. Such systems may also be verysmall and passive, in which a transponder receives power from the basestation or reader only when information is desired to be transmitted orexchanged.

A typical RFID system includes a reusable identifying device typicallyreferred to as a tag, but sometimes designated as a “card,” “key,” orthe like. The RFID system also requires a recognition or reader stationthat is prepared to recognize identifying devices of predeterminedcharacteristics when such identifying device is brought within theproximity of the reader station. Typically, a reader station includes anantenna system that reads or interrogates the tags via a radio frequency(RF) link and a controller. The controller directs the interrogation ofthe tags and may provide memory for storing the data collected from thetags. Further, the controller may provide a user interface so that auser may externally monitor the data.

In operation, as a tag comes within sufficient proximity to an RFIDreader station, the antenna emits RF signals towards the tag and the tagtransmits responses to the antenna. The tags can be powered by aninternal battery (an “active” tag) or by inductive coupling receivinginduced power from the RF signals emitted from the antenna (a “passive”tag). Inductive coupling takes place between the two devices when theyare proximate to one another; physical contact is unnecessary. Passivetags have zero maintenance and virtually unlimited life. The life spanof an active tag is, however, limited by the lifetime of the battery,although some tags offer replaceable batteries.

Current monitoring systems with RFID tags have not been adapted for usewith fuel cell systems, either in terms of the type of data desired tobe monitored or in terms of the ability of the system to withstand theharsh environment due to contact with fuel cell fuels. It would,therefore, be desirable to provide an RFID monitoring system and othertypes of monitoring systems for use with a fuel cell system.

SUMMARY OF THE INVENTION

Briefly, in accordance with one aspect of the present invention, asystem for monitoring a fuel cell includes a fuel cell supply connectedto a fuel cell. A plurality of sensors is operatively connected to thefuel supply. A controller is connected to the fuel cell and to anoptional information storage device. A sensor communication linkconnects the plurality of sensors and the controller. A memorycommunication link connects the controller and the optional informationstorage device

According to another aspect of the present invention, a fuel supply fora fuel cell includes a container having fuel disposed therewithin. Asensor for monitoring a condition of the fuel is located on or withinthe fuel supply. An RFID tag is configured to communicate with thesensor and adapted to be interrogated by an RFID reader station.

According to another aspect of the present invention, a fuel supply fora fuel cell includes at least one optical sensor, such as a coloridentification tag or a sensor located on an optical fiber, disposed onor within the supply. A device powered by the fuel cell, a functionalunit connected to the fuel cell or the fuel cell may contain a colorreader capable of reading the optical sensor to confirm that a properfuel supply has been inserted or to monitor the condition(s) of the fuelsupply, e.g. temperature and pressure.

According to another aspect of the present invention, a method formonitoring a condition of fuel within a fuel cell comprises the steps of(1) providing a fuel cell connected to a fuel supply containing a fuel;(2) collecting data regarding the fuel using a plurality of sensors; (3)relaying the information from the sensor to a controller and optionallyto an information storage device, wherein the plurality of sensors islocated in or on the fuel supply and the information storage device islocated remotely from the plurality of sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a perspective break-away view of a fuel cell system accordingto the present invention;

FIG. 1 a is a schematic view of an alternate embodiment of a fuel cellsystem according to the present invention incorporating passive opticalsensors;

FIG. 2 is a schematic view of a fuel cell system according to thepresent invention, wherein a sensor array is connected to a remotelylocated controller and information storage device;

FIG. 3 is a schematic view of a fuel cell system according to thepresent invention, wherein a monitoring system in a fuel cartridge isremotely linked to a controller and information storage device;

FIG. 4 is a schematic view of a second embodiment of the fuel cellsystem of the present invention, wherein sensors of the monitoringsystem are remotely linked to an RFID tag;

FIG. 5 is a schematic view of a fuel cell system according to a thirdembodiment of the present invention, wherein the RFID tag is fixedlyattached to an interior surface of the fuel cartridge;

FIG. 6 is a schematic view of a fuel supply according to the presentinvention having an RFID tag affixed to an outer surface thereof;

FIG. 7 is a schematic view of a fuel supply according to the presentinvention having an RFID tag affixed to an outer surface thereof with aninsulating materials; and

FIG. 8 is another embodiment similar to FIG. 1 illustrating an alternatecolor I.D. tag.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As illustrated in the accompanying drawings and discussed in detailbelow, the present invention is directed to a fuel supply, which storesfuel cell fuels such as methanol and water, methanol/water mixture,methanol/water mixtures of varying concentrations or pure methanol.Methanol is usable in many types of fuel cells, e.g., DMFC, enzyme fuelcell and reformat fuel cell, among others. The fuel supply may containother types of fuel cell fuels, such as ethanol or other alcohols,chemicals that can be reformatted into hydrogen, or other chemicals thatmay improve the performance or efficiency of fuel cells. Fuels alsoinclude potassium hydroxide (KOH) electrolyte, which is usable withmetal fuel cells or alkali fuel cells, and can be stored in fuelsupplies. For metal fuel cells, fuel is in the form of fluid-borne zincparticles immersed in a KOH electrolytic reaction solution, and theanodes within the cell cavities are particulate anodes formed of thezinc particles. KOH electrolytic solution is disclosed in United Statespublished patent application no. 2003/0077493, entitled “Method of UsingFuel Cell System Configured to Provide Power to One or more Loads,”published on Apr. 24, 2003, which is incorporated herein by reference inits entirety. Fuels also include a mixture of methanol, hydrogenperoxide and sulfuric acid, which flows past a catalyst formed onsilicon chips to create a fuel cell reaction. Fuels also include a blendor mixture or methanol, sodium borohydride, an electrolyte and othercompounds, such as those described in U.S. Pat. Nos. 6,554,877,6,562,497 and 6,758,871, which are incorporated by reference in theirentireties. Fuels also include those that are partially dissolved insolvent and partially suspended in solvent, described in U.S. Pat No.6,773,470 and those that include both liquid fuel and solid fuels,described in United States published patent application number2002/076602. Both of these references are also incorporated by referencein their entireties.

Fuels also include metal hydrides, such as sodium borohydride (NaBH₄)and water, discussed above. Fuels further include hydrocarbon fuels,which include, but are not limited to, butane, kerosene, alcohol andnatural gas, disclosed in United States published patent application no.2003/0096150, entitled “Liquid Hereto-Interface Fuel Cell Device,”published on May 22, 2003, which is incorporated herein by reference inits entirety. Fuels also include liquid oxidants that react with fuels.The present invention is, therefore, not limited to any type of fuels,electrolytic solutions, oxidant solutions or liquids or solids containedin the supply or otherwise used by the fuel cell system. The term “fuel”as used herein includes all fuels that can be reacted in fuel cells orin the fuel supply, and includes, but is not limited to, all of theabove suitable fuels, electrolytic solutions, oxidant solutions, gasses,liquids, solids and/or chemicals and mixtures thereof.

As used herein, the term “fuel supply” includes, but is not limited to,disposable cartridges, refillable/reusable cartridges, containers,cartridges that reside inside the electronic device, removablecartridges, cartridges that are outside of the electronic device, fueltanks, fuel reservoirs, fuel refilling tanks, other containers thatstore fuel and the tubings connected to the fuel tanks and containers.While a cartridge is described below in conjunction with the exemplaryembodiments of the present invention, it is noted that these embodimentsare also applicable to other fuel supplies and the present invention isnot limited to any particular type of fuel supplies.

The fuel supply of the present invention can also be used to store fuelsthat are not used in fuel cells. These applications include, but are notlimited to, storing hydrocarbons and hydrogen fuels for microgas-turbine engines built on silicon chips, discussed in “Here Come theMicroengines,” published in The Industrial Physicist (December2001/January 2002) at pp. 20-25. Other applications include storingtraditional fuels for internal combustion engines; hydrocarbons, such asbutane for pocket and utility lighters and liquid propane; as well aschemical fuels for use in personal portable heating devices. As usedherein, the term “fuel cell” includes fuel cells as well as othermachineries usable with the cartridges of the present invention.

As illustrated in the figures, the present invention is directed to afuel cell system 10 for powering a load 11 (shown in FIGS. 2-5). Load 11is typically an electronic device that fuel cell system 10 powers. Loador electrical device 11 is preferably the external circuitry andassociated functions of any useful consumer electronic device, althoughload 11 may also have fuel cell system 10 integrated therewith. Examplesof electronic device 11 include, but are not limited to, mobile or cellphones, calculators, power tools, gardening tools, personal digitalassistants, digital cameras, laptop computers, computer games systems,portable music systems (MP3 or CD players), global positioning systems,and camping equipment, among others.

Referring to FIG. 1, the first embodiment of fuel cell system 10includes a fuel cell 9 having a fuel cell housing 17 and a fuel supply12 having a fuel supply housing 21. Also contained within fuel cellhousing 17 is preferably a pump 14 for transferring fuel from fuelsupply 12 to fuel cell units 16. Suitable pumps 14, including but notlimited to piezo-electric pumps, are fully disclosed in the patentpublication no. U.S. 2005/0118468, and also in commonly owned,co-pending United States patent publication nos. U.S. 2004/0151962;entitled “Fuel Cartridge for Fuel Cells,” filed on Jan. 31, 2003, U.S.2005/0023236; entitled “Fuel Cartridge with Flexible Liner,” filed onJul. 29, 2003; and U.S. 2005/0022883, entitled “Fuel Cartridge withConnecting Valve,” filed on Jul. 29, 2003. The disclosures of thesereferences are incorporated herein by reference in their entireties. Inanother embodiment, fuel supply 12 is a pressurized fuel supply, whichautomatically controls the amount of fuel transferred to fuel cell 9based upon the internal pressure of fuel supply 12 as discussed in theU.S. 2005/0023236 publication, among other references. As is describedin commonly owned, co-pending U.S. patent application publication nos.2005/0074643, entitled “Fuel Cartridges for Fuel Cells and Methods forMaking Same,” filed on Oct. 6, 2003; Ser. No. 11/067,167, entitled“Hydrogen Generating Fuel Cell Cartridges,” filed on Feb. 25, 2005; andSer. No. 11/066,573, entitled “Hydrogen Generating Fuel CellCartridges,” filed on Feb. 25, 2005, as well as commonly-owned,co-pending U.S. provisional application Ser. No. 60/689,538, entitled“Hydrogen-Generating Fuel Cell Cartridges,” and 60/689,539, entitled“Hydrogen-Generating Fuel Cell Cartridges,” both of which were filed onJun. 13, 2005, the internal pressure of fuel supply dictates whether ornot additional fuel is produced within the fuel supply. The disclosuresof all of the above-listed references are incorporated herein byreference in their entireties. In this case, the internal pressure ofthe pressure cartridge is preferably monitored with a pressure sensor.

Fuel cell 9 includes several fuel cell units 16 arranged into stacks.Fuel cell units 16 may be any type of fuel cell unit known in the art,as discussed above. Fuel cell units 16 may include at least a PEMsandwiched between an anode layer and a cathode layer. Typically,several sealing layers are also included with fuel cell unit 16. Asdescribed above, fuel cell units 16 generate free electrons, i.e.,electricity, to power electronic device 11.

With further reference to FIG. 1, fuel supply 12 comprises an outershell or casing 21 and a nozzle 22. Nozzle 22 houses shut-off valve 24(shown in FIGS. 2-5), which is in fluid communication with the fuelstored in fuel supply 12. Shut-off valve 24 in turn is connected to pump14. Suitable shut-off valves 24 are fully disclosed in publication U.S.2005/0022883. Pump 14 is optional if fuel supply 12 is pressurized; insuch a case, pump 14 may be replaced by a valve.

The size and shape of fuel cell housing 17 need only be sufficient tocontain fuel cell units 16, pump 14, controller 18, and informationstorage device 13. Fuel cell housing 17 is also preferably configured toreceive fuel cartridge housing 21. Housing 17 is preferably configuredsuch that fuel supply 12 is easily connectable to housing 17 by theconsumer/end user. Supply 12 can be formed with or without an innerliner or bladder. Cartridges without liners and related components aredisclosed in publication U.S. 2004/0151962. Cartridges with inner linersor bladders are disclosed in publication U.S. 2005/0023236.

Controller 18 is preferably provided within housing 17 to control thefunctions of electronic device 11, supply 12, pump 14 and fuel cellunits 16, among other components. Alternatively, controller 18 may beremotely located from fuel cell system 10 and connected thereto via acommunications transmission link, such as a radio frequency link or anoptical link. Preferably, housing 17 also supports at least one optionalbattery 19 for powering various components of system 10 and electronicdevice 11 when fuel cell 9 is not operating or during system start-up,shut down, or when otherwise necessary. Alternatively, optional battery19 powers controller 18 when fuel supply 12 is empty or when the fuelcell 9 is off. Optional battery 19 can be replaced by or used inconjunction with solar panels. Additionally, optional battery 19 may berecharged by fuel cell 9 or another appropriate source, such as a walloutlet or solar panels.

In the present invention, a monitoring system is included with fuel cellsystem 10. Monitoring system includes a plurality of sensors 30 formonitoring one or more parameters of the fuel contained within fuel cellsupply 12. In the first embodiment as shown in FIG. 1, plurality ofsensors 30 are located on a single sensor chip 28, which is preferablyan integrated circuit chip. Preferably, neither plurality of sensors 30nor sensor chip 28 contain memory; the information gathered by sensors30 are relayed to controller 18 and could be stored in informationstorage device 13, which is described in greater detail hereinafter. Inan alternate embodiment, however, sensor chip 28 may contain memorysimilar to information storage device 13.

Typically, several fuel parameters should be monitored. For example, theparameters include but are not limited to pressure, temperature, thepresence and levels of dissolved gasses, ion concentrations, fueldensity, the presence of impurities, duration of use, stress and strainto which fuel supply is subjected, as well as the amount of fuelremaining within the fuel cartridge. Preferably, at least one of sensors30 is a pressure sensor. The pressure sensor may be any type of pressuresensor known in the art that is capable of being placed in fuel supply12 and measuring pressure in the anticipated range of approximately 0-40psi, although this range may vary depending upon the fuel cell systemand fuel used. For example, the pressure sensor may be a pressuretransducer available from Honeywell, Inc. of Morristown, N.J. Thepressure sensor may also be a glass or silica crystal that behaves likea strain gauge, i.e., the crystal emits a current depending upon theamount of pressure. The pressure sensor may be used alone or inconjunction with other sensors monitoring different aspects of the fuel.

The pressure can also be sensed by a piezoelectric sensor. Piezoelectricsensors are solid state elements that produce an electrical charge whenexposed to pressure or to impacts. Changes in pressure inside the fuelsupply due to internal pressure or impacts cause a signal to be producedfrom the sensor, which can be transmitted to the controller forprocessing or action. Suitable piezoelectric sensors are available frommany sources, including PCB Piezotronics. Additionally, thepiezoelectric sensor can also be configured to measure a force acting onthe fuel supply or on the fuel cell system, and can also act as anaccelerometer so that if the fuel supply is dropped the sensor wouldrecognize the acceleration and signals the controller for actions, e.g.,shut down or fail-safe operations. The piezoelectric sensors can belocated on fuel supply 12, on fuel cell system 10 or on electronicdevice 11.

The pressure can also be sensed by an optical sensor. The use of passiveoptical sensors is well known, as discussed, for example, in U.S. Pat.No. 4,368,981, the disclosure of which is incorporated herein in itsentirety by reference. As shown in FIG. 1A, fuel cell 9 includes a lightsource 60, such as a variable wavelength laser, a light emitting diode,or similar source of visible or non-visible radiation. Fuel cell 9 alsoincludes at least one photodetector 64. Both light source 60 andphotodetector 64 are linked to controller 18. An optically invisiblewindow 62 a is disposed on a surface of housing 17 facing fuel supply 12so that the aperture of light source 60 is aligned with window 62 a.Similarly, a second optically invisible window 62 b is disposed on asurface of casing 21 so that when fuel supply 12 is attached to fuelcell 9, window 62 a aligns with window 62 b. Optically connected towindow 62 b within fuel supply 12 is at least one sensor 30. One ofsensors 30 can be optical sensor 61 which may be any passive opticalsensor known in the art, such as an interferometer, a Michelson sensor,a Fabry-Perot sensor and the like. In one embodiment, optical sensor 61generally includes two coils of optical fiber which initially have thesame length. An exposed optical fiber 63 a is subjected to environmentalconditions within fuel supply 12, while a reference coil of opticalfiber 63 b is shielded therefrom. In one example, exposed coil 63 a iswrapped around a fuel liner and reference coil 63 b is positioned insidethe fuel liner, on an exterior surface of the outer casing, or betweenthe fuel liner and the outer casing. If the pressure in the fuel linerincreases then the liner would increase in volume, thereby stretchingthe exposed fiber. The difference between the exposed and the referencecoils indicates an increase in pressure. Additionally since both fibercoils are at substantially the same temperature, this optical sensor isnot sensitive to temperature. In the event that the exposed fiber isbroken due to the pressure in the liner, the failure of the light inexposed coil 63 a to reach photodetector 64 or optional photodetector 64a may also indicate high pressure.

In operation, light source 60 emits light, preferably a pulse of knownduration, which shines through window 62 a and into window 62 b. Thelight is optically transferred to both coils 63 a, 63 b at the sametime. The light travels through coils 63 a, 63 b and is reflected backthrough windows 62 b and 62 a. The light signals are detected byphotodetector 64. Optionally, photo detector 64 comprises detectors 64a, 64 b corresponding to coils 63 a and 63 b. As pressure increaseswithin fuel supply 12, the length of exposed coil 63 a increasesrelative to the length of reference fiber 63 b, causing a slight delayin receiving the signal from coil 63 a. From this time delay, thepressure within fuel supply 12 may be calculated by controller 18.

One of sensors 30 may also be a temperature sensor. The temperaturesensor can be any type of temperature sensor known in the art, such as athermocouple, a thermistor, or an optical sensor. Anticipated typicaltemperatures desired to be monitored range from about −20 to 55 degreescentigrade. A temperature sensor may be used alone or in conjunctionwith other sensors monitoring different aspects of the fuel. If anoptical sensor is used, the type and method of operation thereof issubstantially similar to that described above with respect to thepressure within fuel supply 12.

One of sensors 30 may also be a sensor for measuring dissolved gases,such as an oxygen or hydrogen sensor. These dissolved gas sensors may beany type known in the art. For example, one type of appropriate oxygensensor is a galvanic cell, including an anode and a cathode surroundedby an electrolytic solution. The galvanic cell produces an electriccurrent proportional to the pressure of detected oxygen. The dissolvedgas sensor may be used alone or in conjunction with other sensorsmonitoring different aspects of the fuel.

One of sensors 30 may be a fuel gauge. One type of fuel gauge suitablefor use on a chip 28 is a thermistor (also thermister) which can be usedto measure the remaining fuel in fuel supply 12. A thermistor is asemi-conducting resistor that is sensitive to temperature changes. Inother words, the resistance of the thermistor changes as the temperaturechanges. Generally, there are two types of thermistors: negativetemperature coefficient (NTC) thermistors and positive temperaturecoefficient (PTC) thermistors. NTC thermistors display a decrease in itsresistance when exposed to increasing temperature, and PTC thermistorsdisplay an increase in its resistance when exposed to increasingtemperature. Thermistors have been traditionally used to measure thetemperature of a system or a fluid. The use of thermistors as a fuelgauge is discussed in detail in patent application publication no. U.S.2005/0115312, which is incorporated by reference in its entirety.

An important aspect of the thermistor's resistance depends on thethermistor's body temperature as a function of the heat transfer insidethe fuel cartridge and the heat transfer within the electronic devicethat the fuel cell powers. Heat transfer occurs mainly by conduction andradiation in this environment or from heating caused by powerdissipation within the device. In traditional temperature measuringfunction, self heating must be compensated so that the accuratetemperature can be obtained. In accordance with the present invention,self heating is not compensated so that the capacity to dissipate heatof the remaining fuel inside fuel cartridge can be gauged. The heatcapacity is related to the amount of fuel remaining in the cartridge.Both NTC and PTC thermistors are usable with the present invention.

Generally, heat capacitance or heat conductivity is described as theability of a fluid, i.e., liquid or gas, to conduct or dissipate heat.Liquid, such as water or methanol, has a much higher capacity todissipate heat than gas, such as air, carbon dioxide or methanol gas.The capacity of a fluid to dissipate heat is equal to its heatcapacitance, which is a constant for a particular fluid, multiplied bythe fluid volume. Hence, this aspect of the present invention measuresthe volume of the remaining fuel by measuring the electrical resistanceof the thermistor positioned within the fuel or on the optional linercontaining the fuel. The electrical resistance is then converted to thecapacity of the remaining fuel to dissipate heat, and this capacity isconverted to the volume of remaining fuel by dividing out the heatcapacitance constant. In other words, higher heat capacity correspondsto higher remaining fuel volume.

The thermistor-fuel gauge should be calibrated prior to use. Theoperating temperatures of the fuel cell and of the electronic device areknown. An electrical signal from a full liner is recorded and then anelectrical signal from an empty liner is recorded. One or more signalsfrom known partial volumes can also be recorded. A calibration curve canbe drawn from these calibration points between these operatingtemperatures. A real-time signal is compared to this calibration curveto determine the remaining fuel. Other methods of calibrations can beperformed without deviating from the present invention.

Additionally, since the thermistor is a resistor, electrical currentthat flows through the thermistor generates heat. Therefore, electricalcurrent can flow through the thermistor to generate heat that can bedissipated by the remaining fuel, and accurate readings can be obtained.In one embodiment, controller 18 sends the current as a query to thethermistor to gauge the amount of heat dissipation whenever a remainingfuel reading is desired. The electrical current can be sentintermittently or continuously.

In accordance with another aspect of the present invention, athermocouple can be used as a fuel gauge. The use of a thermocouple as afuel gauge is described in detail in publication U.S. 2005/0115312,previously incorporated by reference. A thermocouple is also typicallyused to measure temperature and comprises two wires made from differentmetals, and is also known as a bi-metal sensor. The wires are joined attwo junctions. A potential difference is established when a measuringjunction is at a temperature that is different than a temperature at areference junction. The reference junction is typically kept a knowntemperature, such as the freezing point of water. This potentialdifference is a DC voltage which is related to the temperature at themeasuring junction. Using a thermocouple to measure temperature is wellknown in the art.

Similar to the thermistor, a thermocouple acts like a resistor that issensitive to temperature. The thermocouple is capable of measuring theheat capacity of the remaining fuel by measuring the potentialdifference. Hence, the thermocouple can also measure the remaining fuel.Alternatively, electrical current can be sent through the measuringjunction of the thermocouple. The current heats up the measuringjunction and the fuel dissipates the heat. The amount of heatdissipated, therefore, relates to the remaining fuel. The current can besent intermittently or continuously. The thermocouple fuel gauge shouldbe calibrated similar to the calibration of the thermistor, discussedabove.

In accordance with another aspect of the present invention, an inductivesensor can be used to measure the remaining fuel. The use of inductivesensors as a fuel gauge is described in detail in publication no. U.S.2005/0115312, previously incorporated by reference. Inductive sensorsare typically used as on/off proximity switches. An inductive sensorcontains a wire coil and a ferrite core, which form the inductiveportion of an inductive/capacitance (LC) tuned circuit. This circuitdrives an oscillator, which in turn generates a symmetrical, oscillatingmagnetic field. When an electrical conductor, such as a metal plate,enters this oscillating field, eddy currents are formed in theconductor. These eddy currents draw energy from the magnetic field. Thechanges in the energy correlate to the distance between the inductivesensor and the electrical conductor.

One of sensors 30 may also be a clock or other form of timing orcounting mechanism. Examples of the timing mechanism may include anoscillator, such as a crystal or induction oscillator, integrated ontochip 28. As the counter relies upon memory such as information storagedevice 13, which is preferably housed in fuel cell 9, the counter countsthe oscillations only when fuel supply 12 is connected to fuel cell 9.In this way, the counter may track how long fuel supply 12 has been inuse. The count of oscillations is preferably stored in informationstorage device 13. The oscillator can be powered by an optional batteryinternal to fuel supply 12 or may be triggered by power transferred fromfuel cell 9, such as when pump 14 is turned on. If information storagedevice 13 also tracks pumping rates, controller 18 may be programmed tocalculate flow rate of fuel through pump 12 and, consequently, theremaining fuel in fuel supply 12. In other words, the combination of acounter and tracking of pumping rates may be used as a fuel gauge.

Alternatively, the timing mechanism may include an energy storage devicewith a known decaying signature housed in fuel supply 12. For example,fuel supply 12 could include a battery whose self-discharge rates areknown and a battery tester may be incorporated into fuel cell 9. It isknown in the art that a typical nickel-based battery dischargesapproximately 10-15% of its charge in the first 24 hours after thecharge is maximized, followed by additional 10-15% losses monthlythereafter. Similarly, it is known that lithium ion batteriesself-discharge about 5% in the first 24 hours after charge and 1-2%monthly thereafter. Additional information regarding the self-dischargeof batteries and monitoring devices therefor can be found in IsidorBuchmann, The Secrets of Battery Runtime (April 2001) available on<http://www.batteryuniversity.com/parttwo-31.htm>, the disclosure ofwhich is incorporated herein by reference. By programming controller 18and information storage device 13 with the self-discharge curves ofbatteries that are always fully charged when installed in or on fuelsupply 12, controller 18 can calculate the age or shelf life of fuelsupply 12 based on the measured charge level of the battery at any pointin time after fuel supply 12 is attached to fuel cell 9.

Additionally, the monitoring system should be robust. Fuels, in general,may have degrading effects on materials exposed to the fuel, and inaccordance with one aspect of the present invention materials for themanufacture of fuel supply 12 and its components are selected to becompatible with fuels. Chip 28 and/or sensors 30 may be placed incontact with the fuel, such as floated in the fuel or affixed to aninner surface of casing 21 or the optional liner. Therefore, themonitoring system should be able to withstand sustained contact with thefuels used in fuel cells.

A suitable protective material is silicon dioxide (SiO₂), which can beapplied by vapor deposition or sputtering technique or other knownmethods. Silica molecules coalesce on a substrate as SiO_(x) where x is1 or 2. Any protective material that can be suspended in a solvent canbe used.

Other suitable coatings include, but are not limited to, the class ofepoxy-amine coatings. Such coatings are commercially available asBairocade coatings from PPG Industries, Inc. of Cleveland, Ohio. Thesetypes of coatings can be applied using electro-static guns and cured ininfrared ovens to create the gas barrier. The coatings can also beapplied by dipping, spraying or painting. These coatings are typicallyused to coat beverage bottles or cans to protect the beverages inside.

Additionally, a clear polycrystalline, amorphous linear xylylene polymermay coat and protect the sensor. Xylylene polymer is commerciallyavailable as Parylene® from Cookson Specialty Coating Systems ofIndianapolis, Ind. Three suitable Parylene resins are Parylene N(poly-para-xylylene), Parylene C (poly-monochloro-para-xylylene) andParylene D (poly-dichloro-para-xylylene). Additional discussion ofParylene can be found in co-owned, co-pending United States patentpublication no. 2006/0030652, entitled “Fuel Supplies for Fuel Cells,”filed on Aug. 6, 2004, the disclosure of which is hereby incorporated byreference herein in its entirety.

In accordance with another aspect of the present invention, a gasbarrier film is wrapped around sensors 30 for protection. Suitable gasbarrier films include Mylar® from DuPont and various films from the foodpackaging industry. More detailed information regarding gas barrierfilms, including a list of appropriate films, may be found inpublication no. U.S. 2006/0030652, previously incorporated by reference.Other appropriate materials include polyvinyl alcohol (PVOH), ethylenevinyl alcohol (EVOH), EVOH bonded to a polyester substrate,polyvinylidene chloride copolymers (PVDC or Saran), nylon resins,fluoro-polymers, polyacrylonitrile (PAN), polyethylene naphthalate(PEN), poly(trimethlylene terephthalate) (PTT), resorcinol copolymers,liquid crystal polymers, aliphatic polyketones (PK), polyurethane,polyimide, and blends and copolymers of these materials.

Furthermore, sensor 30 may be protected from the fuel by virtue of beingplaced within housing 21 but outside of a bladder or liner, such asliner 27 as shown in FIG. 2 and discussed in greater detail below.Additional protective coatings and protective films suitable for thesensors are disclosed in publication no. U.S. 2006/0030652.

Referring again to FIG. 1, as chip 28 and information storage device 13are preferably located remote from one another, controller 18 initiatesthe gathering of information from sensors 30, for example, when fuelsupply 12 is first inserted into fuel cell 9. Controller 18 can transmita signal and/or power to chip 28 to interrogate the sensors 30. Sensors30 then take readings which are preferably passed back to controller 18.The communication between controller 18 and chip 28 takes place via alink that, in this embodiment, is hard-wired. Leads 70, preferablyelectrical wires, are connected to chip 28 and electrical contacts 15A,which are disposed on an exterior face of casing 21. Leads 72, alsopreferably electrical wires, are connected to controller 18 andelectrical contacts 15B. As will be apparent to those in the art, leads70, 72 and contacts 15A, 15B may be any leads or electrical contactsknown in the art. Electrical contacts 15A and 15B are configured andlocated such that an electrical connection is established betweencontroller 18 and chip 28 if fuel supply 12 is properly inserted intohousing 17. To that end, fuel supply 12 and housing 17 are preferablyconfigured such that fuel supply 12 may only be inserted into housing 17in the proper position. For example, housing 17 may include tabs thatprotrude into the cavity for receiving fuel supply 12, and fuel supply12 may include coordinating slots into which the tabs may slide. Anotherexample would be if the perimeter of the cavity on housing 17 forreceiving fuel supply 12 is of an asymmetrical shape and fuel supply 12has the same shape. Additional ways to insure proper positioning of fuelsupply within housing 17 are discussed in commonly owned, co-pendingU.S. application Ser. No. 10/773,481, entitled “Datum BasedInterchangeable Fuel Cell Cartridges,” filed on Feb. 06, 2004, thedisclosure of which is hereby incorporated herein by reference in itsentirety.

In other embodiments, the communication link between sensors 30 andcontroller 18 is a wireless system that is capable of transmittingelectrical signals. Suitable wireless transmission systems include anywireless transmission systems known in the art, including, inter alia,Blue Tooth technology, radio frequency, infrared rays, and lighttransmissions such as from lasers or LEDs from the fuel cell 9 side tophotonic sensors on fuel supply 12. Such wireless transmissions can alsotransmit or transfer power to sensors 30.

As described in publication no. U.S. 2005/0118468, the fuel supply mayinclude an information storage device that possesses an ability to storeinformation such as fuel content including fuel content during usage,fuel quantity, fuel type, anti-counterfeit information, expiration datesbased on age, manufacturing information and to receive information suchas length of service, number of refuels, and expiration dates based onusage.

Information relating the conditions of the fuel may change over time,and it is useful to monitor and store such information. However, theconditions of the fuel, e.g., viscosity as a function of temperaturediscussed above, can change from the time electronic device 11 is turnedoff until it is turned on again, e.g., between nighttime and daytime.Hence the information stored on a memory device when the device isturned off may be stale when the device is turned on again. Hence, incertain circumstances it is desirable to interrogate sensors 30 insteadof reading the information stored on information storage device 13.Stored information includes protectable information and rewriteableinformation.

Protectable information, which cannot be easily erased, includes, but isnot limited to, type of cartridge; date the cartridge was manufactured;lot number for the cartridge; sequential identification number assignedto the cartridge during manufacturer; date the information storagedevice was manufactured; lot number for the information storage device;sequential identification number assigned to the information storagedevice; machine identification number for the cartridge and/or storagedevice; shift (i.e., time of day) during which the cartridge and/orstorage device were produced; country where the cartridge and/or storagedevice were produced; facility code identifying the factory where thecartridge and/or storage device were produced; operating limits,including but not limited to temperature, pressure, vibration tolerance,etc.; materials used in manufacturing, anti-counterfeit information;fuel information; such as chemical formulation; concentration; volume;etc.; intellectual property information, including patent numbers andregistered trademarks; safety information; security password oridentification; expiration date based on date of manufacturing;shut-down sequence; hot swap procedure; recycling information; reactantinformation; fuel gage type; new software to update fuel cell 9 and/orcontroller 18; and fluid sensor information.

Rewriteable information includes, but is not limited to, current fuellevel and/or current ion level in the fuel; number ofejections/separations of the cartridge from the electrical device and/orfuel cell or number of times that the cartridge was refilled; fuel levelon ejection/separation of the cartridge from the electrical deviceand/or fuel cell; number of insertions/connections of the cartridge tothe electrical device and/or fuel cell; fluid level oninsertion/connection of the cartridge to the electrical device and/orfuel cell; current operation status including rate of power consumption;acceptance/rejection of a particular electronic device; maintenancestatus and marketing information for future cartridge designs;triggering events; expiration date based on actual usage; efficiency ofthe system; operational history of the fuel cell system; such astemperatures and pressures during selected time periods (e.g., atstart-ups and shut-downs or periodically); and operational history ofthe electronic devices, such as number of digital pictures percartridge, maximum torque for power tools, talling minutes and standbyminutes for cell phones, number of address look-ups per cartridge forPDAs, etc.

Information storage device 13 is preferably an electrical storagedevice, such as an EEPROM memory chip as discussed and disclosed inpublication no. U.S. 2005/0118468, previously incorporated by reference.Suitable information storage devices include, but are not limited to,random access memory (RAM), read-only memory (ROM), programmableread-only memory (PROM), erasable programmable read-only memory (EPROM),electrically erasable programmable read-only memory (EEPROM), flashmemory, electronically readable elements (such as resistors,capacitance, inductors, diodes and transistors), optically readableelements (such as bar codes), magnetically readable elements (such asmagnetic strips), integrated circuits (IC chips) and programmable logicarrays (PLA), among others. The preferred information storage deviceincludes PLA and EEPROM, and the present invention is described hereinwith the EEPROM. However, it is understood that the present invention isnot limited to any particular type of information storage device.

Preferably, information storage device 13 generally has a substrate (notshown) formed of a “potting material,” an integrated circuit memory chip(not shown), and etched or printed layers or strips of electricalcircuitry or contacts (not shown). The integrated circuit memory chip(not shown) can be connected to the substrate (not shown) with aplurality of pins, such as in an external electronic connector.

Information storage device 13 is preferably connected to controller 18via link 25, preferably an electrical connection. Alternatively, link 25is a wireless system that is capable of transmitting electrical signalsbetween information storage device 13 and controller 18. Suitablewireless transmission systems include any wireless transmission systemsknown in the art, such as Blue Tooth technology, radio frequency,infrared rays, optical transmissions, etc.

Information storage device 13 can have any particular memory size. Thememory size is determined by the amount of data needed to be stored.Suitable memory size typically ranges from about 128 bytes to about 512K bytes. Memory sizes of 1M bytes and higher are also commerciallyavailable and are usable in the present invention. Information storagedevice 13 is also not limited to any particular dimensions so long thatit can fit within housing 17 of fuel cell 9.

Information storage device 13 preferably includes portions 13 a and 13b. Portion 13 a is pre-programmed or set up by the manufacturer toinclude read-only (write protected or protectable) data, discussedabove. Controller 18 can read the data in portion 13 a of informationstorage device 13. However, the controller 18 cannot modify or erase theread-only data in portion 13 a. Portion 13 b is programmed or set up bythe manufacturer to include rewriteable data, discussed above.Controller 18 can read and write/erase the data in portion 13 b.Portions 13 a and 13 b are electrically connected to link 25 viaconventional electrical wires or printed circuit boards, etc., known bythose of ordinary skill in the art or by the wireless connections listedabove.

A second embodiment of the present invention is shown in FIG. 2. In thisembodiment, which is similar to the first embodiment shown and describedwith respect to FIG. 1, plurality of sensors 30 is not contained on achip, but is preferably distributed throughout fuel supply 12. Fuelsupply 12 preferably includes a liner 27.

In this embodiment, a fuel gauge may comprise two sensors placed withinor on fuel supply 12. The first sensor should be placed on a locationthat moves as the fuel is removed to reflect the level of fuel remainingin the cartridge. For example, the first sensor can be placed directlyon liner 27. The second sensor is positioned outside of fuel supply 12,e.g., on fuel cell 9 or electronic device 11. The second sensor iselectrically connected to either fuel cell 9 or to electronic device 11.An electrical circuit connected to the second sensor can measureelectrical or magnetic properties between these sensors, which correlateor are related to the fuel level. The electrical circuit can also beconnected to the first sensor via an electrical wire extending throughthe wall of fuel supply 12. This type of fuel gauge is more completelydescribed in publication no. U.S. 2005/0115312.

The information collected from sensors 30 may be used in a variety ofways. For example, if the temperature of the fuel falls, then the fuelbecomes more viscous and, therefore, harder to pump. Controller 18 maydynamically regulate valve 24 so that sufficient fuel may be pumped tosystem 10. Further, by monitoring the heat cycles to which the fuel issubjected, controller 18 may be programmed to extrapolate the amount offuel remaining in fuel supply 12 and produce a fuel gauge read out.

As will be recognized by those in the art, the placement of sensors 30on or near fuel supply 12 could have many configurations. For example,sensor chip 28 may be separable from fuel supply 12. Fuel supply 12includes at least one port for the transfer of fuel, such as the portclosed by shut-off valve 24. One of these ports could be adapted so thata pod containing sensor chip 28 could be removably inserted therein. Ina case where sensors 30 do not need to be in direct contact with thefuel, such as, for example, if monitoring temperature by contact with abladder or liner within fuel supply 12, an access port for a sensor podcould be placed anywhere on fuel supply 12. Additionally, sensors 30could be located within housing 17 of fuel cell 9. In such a case, theconnection of electrical contacts 15B and 15A (shown in FIG. 1) uponinsertion of fuel supply 12 into housing 17 provides sensors 30 accessto the fuel within fuel supply 12 for monitoring.

In yet another embodiment of the present invention as shown in FIGS.3-5, the monitoring system may also include a radio frequencyidentification (RFID) tag 50 and an RFID tag reader station 52. RFID tag50 may be any RFID tag known in the art. RFID tag 50 may be passive oractive. If RFID tag 50 is active, a power source, such as a battery, isalso required. Generally, RFID tags include memory, either read-only orread-write, and a radio frequency transmitter. However, some RFID tagscontain no memory, such as read-only RFID tags that include hardwiredidentification circuits. The structure and operation of RFID tags aremore fully described in several U.S. patents, including U.S. Pat. Nos.4,274,083 and 4,654,658, the disclosures of which are incorporatedherein by reference. Suitable RFID tags are commercially available frommany sources, including Philips Semiconductors of San Jose, Calif.,among others.

RFID tag 50 preferably includes sufficient read-write memory to containthe data collected from the sensors (described below), although RFID tagmay also be linked via electrical connection to a separate informationstorage device located on fuel cell 9.

RFID tag 50 may be located anywhere on or within fuel supply 12, forexample on the top, bottom, or sides of the exterior surface of theouter casing 21. In the embodiment shown in FIGS. 2, 3, and 4, RFIDtag(s) 50 is disposed within fuel supply 12, i.e., RFID tag 50 isfloated within the fuel. Alternatively, as shown in the embodiment shownin FIG. 5, RFID tag 50 is adhered to an interior surface of fuel supply12 such as by gluing or welding.

RFID tag 50 communicates with RFID reader station 52. RFID readerstation 52 emits a radio frequency signal that communicates with RFIDtag 50 and, in the case of passive RFID tags, powers RFID tag 50 byinduction. As shown in FIGS. 3, 4 and 5, RFID reader station 52 ispreferably located in the body of system 10 separate from fuel supply12. Alternatively, as shown in FIG. 5, RFID reader station 52 may bedisposed on or within electronic device 11 to which system 10 isproviding power. RFID reader station 52 may also be a handheld device orlocated on an external surface of fuel supply 12. RFID reader station 52is also linked, either directly via a hardwired link or indirectly via atransmitted signal, to controller 18. Controller 18 thereby triggers aninterrogation by RFID reader station 52 and also receives theinformation transmitted to RFID reader station 52 from RFID tag 50.

In both of these embodiments, RFID tag 50 should be protected frompossible reaction with the fuel. Preferably, RFID tag 50 may be enclosedor encased in a material that is inert to the fuel. “Inert”, as used inthis context, refers to the ability of the material to withstand lengthyexposure to a fuel such as methanol. For example, RFID tag 50 may bepotted within the same material used to form outer casing 21. RFID tag50 may also be contained within a shell, such as a plastic or metalcapsule, as long as the material chosen for the capsule does notsignificantly interfere with the radio frequency signals transmitted orreceived by RFID tag 50. Additionally, RFID tag 50 may be coated withany of the coating materials described above with respect to sensor(s)30, such as xylylene.

In another embodiment, shown in FIG. 6, fuel supply 12 includes an outercasing 21 made of a metal, such as stainless steel, and fuel containedin a liner 27, similar to the embodiment described above with respect toFIG. 2. In this embodiment, RFID tag 50 is preferably elevated away fromthe surface of outer casing 21 of fuel supply 12 by a mount 78, as outercasing 21 itself may interfere with the induction process that occurswhen RFID reader station 52 is placed in proximity with RFID tag 50. Assuch, RFID tag 50 is preferably spaced away from the surface of outercasing 21, preferably about 5 mm. The actual distance 80, or height ofmount 78, between RFID tag 50 and outer casing 21 depends on manyfactors, including, inter alia, the operating range requirements of thesystem, i.e., the anticipated distance between RFID tag 50 and RFID tagreader station 52, the size of RFID tag 50, and the tuning of RFID tag50 and RFID tag reader station 52. Mount 78 may be made of any material,such as plastic, ceramic, or the like. Mount 78 is preferably affixed toboth outer casing 21 and RFID tag 50 using any method known in the art,such as adhering, such as with an adhesive or similar bonding agent, orby press-fitting mount 78 into a recess formed within outer casing 21.Alternatively, mount 78 can be an air gap.

In addition to spacing RFID tag 50 and outer casing 21 apart, other waysof compensating for the interference of a metal outer casing 21 could beused. For example, as shown in FIG. 7, an insulating material 82 may beplaced between outer casing 21 and RID tag 50. Preferably, insulatingmaterial 82 is a ferrite ceramic material, as the strong magneticproperties of the ferrite shield RFID tag 50 from outer casing 21.Additional ways to overcome the interference of metal outer casing 21include increasing the strength of the reader field generated by RFIDtag reader station 52 and selecting the relative sizes of the of theRFID tag and RFID tag reader station coils.

Sensors 30 may be directly or indirectly linked to RFID tag 50. As shownin FIG. 3, a direct link 40 in this embodiment is an electricalconnection that conveys the data produced by sensor 30 to memory on RFIDtag 50. In other words, sensor 30 and RFID tag 50 may be incorporatedinto one chip prior to insertion into fuel supply 12. Alternatively, asshown in FIG. 4, sensor 30 may itself include a radio frequencytransmitter 41 that modulates and transmits a signal to either RFID tag50 or to controller 18, which also includes a radio frequencytransceiver 43. Sensor 30 may also be integrated with RFID tag 50 withinthe same material to form an RFID package. FIG. 5 shows an embodimentwhere sensors 30 are hardwired to RFID tag 50, which is adhered to aninterior surface of casing 21. It will be recognized that RFID tag 50may also be located on an exterior surface of casing 21.

Additionally, RFID tag 50 may be used to upload new software to fuelcell 9. For example, updated software for controller 18 may be stored inthe memory of RFID tag 50. Upon insertion into housing 17, the newsoftware may be transferred to controller 18 via any of the describedcommunication links. As will be recognized by those in the art, othertypes of information could be stored in the memory of RFID tag 50, suchas product recall alerts, new or updated calibration data, and the like.

In accordance with another aspect of the present invention, sensor 30may comprise at least one color I.D. tag and more specifically at leastone optical color tag. An exemplary fuel supply 12 with color I.D. tags102 is shown in FIG. 8. In one example, color I.D. tag 102 comprises asingle color, which can be accurately measured by a color reader 104located on fuel cell 9. Color reader 104 is connected to processor 18,where the measured color of color tag 102 is processed to determine,among other things, whether the correct fuel supply has been inserted.Suitable color readers include, but are not limited to,spectrophotometers, which are commercially available as the CM seriesfrom Komica Minolta of Japan, and tristimulus type calorimeters,commercially available as the CR-10, CR-11, and CR-13 series from KomicaMinolta. These color readers can provide a digital value representingthe color of color tag 102 and are capable of distinguishing the hues,shade and brightness of a particular color. When the measured colormatches a predetermined value stored in processor 18, then fuel supply12 is accepted.

In another example, color I.D. tag 102 is capable of changing colorresponsive to a condition of fuel supply 12, such as temperature orpressure, among other factors. In this example, color tag 102 is madefrom a material that exhibits chromism, i.e., a reversible change in thecolors of compounds, generally caused by a change in the electron statesof the molecules, induced by various stimuli. Suitable color changingmaterials include thermochromism (induced by heat), photochromism(induced by light, radiation), electrochromism (induced by electronflow), solvatochromism (induced by solvent polarity), ionochromism(induced by ions), halochromism (induced by change in pH), tribochromism(induced by mechanical friction), and piezochromism (induced bymechanical pressure).

A preferred color changing tag 102 is made from a material exhibitingthermochromism, e.g., liquid crystals where the color changes as thecrystallic structure changes from a low-temperature crystallic phasethrough anisotropic chiral/twisted nematic phase to a high-temperatureisotropic liquid phase. Exemplary color changing liquid crystals includecholesteryl nonanoate or cyanobiphenyls. Other suitabletemperature-induced color changing materials include leuco dyes.

In this example, color reader 104 can detect the changes in the color ofcolor tag 102 in response to a physical condition of fuel supply 12,e.g., high temperature or high pressure. The change in color can beprocessed by processor 18 to monitor the condition(s) of fuel supply 12.

In another example color I.D. tag 102 comprises a plurality of colors,e.g., parallel strips of colors (similar to multi-color barcode). Colorreader 104 is calibrated to scan sequentially across the color strips,and if the color strips are presented in a predetermined pattern, thenthe fuel supply is authenticated. Alternatively, each color strip mayrepresent a unique piece of information. For example, a yellow strip mayindicate fuel type, a blue strip may indicate the particular additivesincluded, another color stripe may indicate the date of manufacture,etc. Processor 18 and color reader 104 may interrogate color I.D.strips/tag 102 to read the information contained on the tag. The coloredstrips may be positioned adjacent to each other or may be spaced apartor separated.

In another example, color reader 104 does not need to scan the coloredstrips, but color reader 104 can take a picture/photo of the entirestrips at once. Digital cameras can be used to capture an image of theentire color tag and the image is compared with a stored image toauthenticate or processed to determine the type of fuel supply, asdiscussed in the previous paragraph. In this example, the pixels in thecaptured image can be compared to the pixels in the stored image todetermine whether the captured image is substantially the same as thestored image. Analog camera also be used, and the images can bedigitized afterward.

In yet another example, color I.D. tag 102 can have any pattern, logo,design or graphic that can be captured by color reader/camera 104 forauthentication or processing. Additionally, tag 102 can be a colorhologram, similar to those used in national currencies worldwide.

Color I.D. tag 102 can be located on housing 21 of fuel supply 12, or itcan be located within fuel supply 12 similar to optical sensor 61 behindwindow 62 b, shown in FIG. 1A.

While it is apparent that the illustrative embodiments of the inventiondisclosed herein fulfill the objectives of the present invention, it isappreciated that numerous modifications and other embodiments may bedevised by those skilled in the art. For example, the fuel cell may beintegrated into load 11. Also, pump 14 may be eliminated if pressurizedfuel supply configurations are used, such as those described in UnitedStates patent publication no. 2005/0074643, the disclosure of which isincorporated herein by reference in its entirety. Additionally,feature(s) and/or element(s) from any embodiment may be used singly orin combination with feature(s) and/or element(s) from otherembodiment(s). Therefore, it will be understood that the appended claimsare intended to cover all such modifications and embodiments, whichwould come within the spirit and scope of the present invention.

1-42. (canceled)
 43. An optical sensor to monitor a fuel supply for afuel cell, said fuel cell comprises a reader capable of reading anoptical signal from said optical sensor to monitor the fuel supply. 44.The optical sensor of claim 43, wherein the fuel cell further comprisesa light source and said light source transports light to the opticalsensor.
 45. The optical sensor of claim 44, wherein the optical sensoris connected to an optical fiber.
 46. The optical sensor of claim 43,wherein the optical sensor comprises a color identification tag.
 47. Theoptical sensor of claim 46, wherein the color identification tagcomprises a plurality of colors.
 48. The optical sensor of claim 46,wherein the color identification tag comprises a color pattern.
 49. Theoptical sensor of claim 46, wherein the color identification comprises amaterial exhibiting chromism.